Method of converting hydrocarbons into organic sulphur compounds



Patented Nov. 19, 1946 UNITED STATES PATENT OFFICE" METHOD OF CONVERTINGHYDROCARBONS INTO ORGANIC SULPHUR COMPOUNDS Carlisle M. Thacher,Highland Park, 111., assignmto The Pure Oil Company, Chicago, 111., acorporation of Ohio No Drawing. Application March 30, 1940, Serial No.326,963

, 2 sures influence the reactions in the desired direction. Typicalreactions which may take place between a normally gaseous paraflinichydrocara minimum of corrosion to the apparatus in which the process isconducted.

Other objects of the invention will become apparent from the followingdescription.

It has been discovered that hydrocarbons can be reacted with sulfur,selenium and sulfur or selenium yielding compounds at elevatedtemperatures in thepresence of a suitable catalyst I pure hydrocarbonssuch as methane, ethane, propane or butane or mixtures thereof or otherhydrocarbons may be used as starting materials. For example, when thestarting material is a hydrocarbon gas such as'methane, the methane isheated and mixed with sulfur vapors and the mixture fed into a reactorwhere the mixed gas and sulfur vapor is contacted with appropriatecatalyst. As catalysts suitable for effecting the conversion ofhydrocarbons to organic sulfur compounds may-be mentioned oxides orsulfides of vanadium, manganese, copper, iron, cobalt, nickel, chromiumand molybdenum. The sulfides of these metals are generally preferred.These compounds may be used alone or supported on materials such assilica gel,- alumina gel, pumice or charcoal, etc., which of themselvesmay possess catalytic activity. The reactants are preferably contactedat temperatures of approximately 400-700 C. and under pressures ofapproximately 1 to 125 atmospheres. While good yields may be obtainedunder a relatively large number bon such as methane and sulfur are asfollows:

The amount of sulfur charged with the hydrocarbon may be varied betweenrather wide limits depending upon a number of factors among which aretime of residence of the reactants in the reaction zone, particularproducts desired and reaction temperature and pressure. Whereintermediate sulfur oxidation products are desired the sulfur should notbe in excess of that necessary to react with the'hydrocarbons to formmercaptans. In general the amount of sulfur charged with the gas ispreferably not in excess of that necessary to stoichiometrically reactwith the hydrocarbon to form the desired organic sulfur compound. Bycontrolling the proportion of sulfur within this range, maximum yieldsof desirable reaction products may be obtained. The reactor as well asthe remainder of the apparatus may be fabricated from ordinary iron,although stainless steel, chromium steel, molybdenum steel, silica,quartz or other materials which are resistant to sulfur corrosion ornonresistant steel lined with a refractory lining such as silica orquartz are preferred.

As shown by the foregoing equations, sulfur may react with hydrocarbongas to form mercaptans, thio-ethers and organic disulfides such asdimethyl disulfide and carbon disulfide. The reaction products arecooled and the organic sulfur compounds separated therefrom byfractionation, absorption in a suitable solvent such as naphtha andsubsequently separated therefrom by fractionation or by other suitablemeans. The

. particular method of separation of reaction products from unreactedmaterials will depend largely upon the composition of the reactionproducts. Any hydrogen sulfide present may be separated from organicsulfur compounds by conventional methods such as by scrubbing with wateror aqueous alkali under appropriate conditions of temperature andconcentration and prior to separation of the organic sulfur compoundsfrom the remaining gases. Unreacted gases may be recycled for furtherreaction. Selenium may be substituted for sulfur when the reactiontemperature is sufficiently high to vaporize selenium. As

sources of sulfur, compounds thereof which readily yield free sulfur.may be used. The apparatus in which the process is carried out may be ofany conventional type consisting of a heating means and reaction chamberwith cooling and fractionating and/or other separating means connectedto the reaction chamber.

In a specific example methane was mixed with sulfur in a ratio of 0.58mol of methane to one incl oi sulfur vapor. calculated as diatomicsulfur, and the mixture contacted with iron sulfide at a space velocityof 775 and at a temperature of 594 to 600 C. Space velocity may bedefined as the ratio of the total volume of vapor charged per hour tothe total volume of-catalyst space. A liquid condensate was obtained,the major portion of which was carbon disulfide and which containedminor portions of intermediate suliur oxidation products. In another runusing the same catalyst, 0.55 mols of methane was mixed with one moi ofsulfur vapor, calculated as diatomic sulfur, and the mixture contactedwith the catalyst at a space velocity of 794 and a temperature of 594 C.to 598 C. A liquid condensate was obtained, the major portion of whichwas carbon disulfide and which containedminor portions of intermediatesulfur oxidation products. In another run at a temperature of 594 C. to599 C. and using a proportion of 5.54 mols of methane to one mol ofsulfur vapor, calculated as diatomic sulfur, the mixture was contactedat a space velocity of 806 with a catalyst consisting of manganesesulflde deposited on Activated alumina in a ratio of 1 to 20. A liquidproduct consisting principally of carbon disulfide and containing minorportions of intermediate sulfur oxidation products,

4 was obtained. In all 0! the foregoing examples pressures slightlyabove atmospheric were employed.

It is not intended that the invention shall be limited by the foregoingspecific examples which are presented for purpose of illustration, butthat the invention shall be limited only by the scope of the claims.

What is claimed is:

1. The method of preparing carbon-sulfur compounds which comprisescontacting parafflnic hydrocarbon gases with sufficient sulfur vapors tostoichiometrically react with the gases to form mercaptans at atemperature of at least 400 0., at which the sulfur and hydrocarbongases chemically react, in the presence of a catalyst selected from thegroup of preformed metal sulfides.

2. Method in accordance with claim 1 in which the temperature is betweenapproximately 400 and 700 C.

3. Method in accordance with claim 1 in which the catalyst is supportedon a carrier selected from the group of silica gel, alumina gel, pumiceand charcoal.

4. Method in accordance with claim 1 which the catalyst is iron sulfide.

5. Method in accordance with claim 1 which the catalyst is cobaltsulfide.

6. Method in accordance with which the catalyst is nickel sulfide.

7. Method in accordance with claim which the catalyst is a sulfideselected from the group consisting of vanadium, manganese, copper, iron,cobalt, nickel, chromium and molybdenum sulfides.

claim 1 CARLISIE M. 'I'HACKER.

